Electrosurgical cutting generally requires a higher output voltage than electrosurgical desiccation. To provide for this, it is known to include within an electrosurgical generator an output transformer which has a higher secondary-to-primary output transformer turns ratio for cutting compared with that used for desiccation. Such increased turns ratio leads to increased demands on the output device driving the transformer, particularly in terms of the peak output current required and power dissipation. To overcome this difficulty, it is known to increase the output impedance of the generator, typically to a value in the range of from 300.OMEGA. to 500.OMEGA.. This may be achieved by providing a low value coupling capacitor but this has the disadvantage of increased voltage drop across the coupling capacitor when used in high load impedance conditions due to the inherent capacitance of the electrode assembly and any cable coupling the electrode assembly to the generator. In effect, the inherent capacitance represents a capacitive load impedance which produces, with the coupling capacitor, a potential divider reducing the voltage delivered across the load. The problem becomes worse when the electrode assembly is placed in a wet field (e.g. in blood or saline solution), since then the effective load capacitance is increased.
It is an object of this invention to overcome this disadvantage.